The Cost Per Kilowatt: Home-Battery Pricing Done Right

We have been writing heavily about batteries recently. We have been discussing everything from their eco-friendliness, the LG Chem Vs Tesla debate, and the coming battery boom.

I don’t know about you, but sometimes after reading everything there is to know about a topic I’m interested in I forget the most basic details… including the price.

So if you guys are anything like me, then you might appreciate this simple price comparison we put together. We looked at a number of different batteries, including the Tesla Powerwall, Redflow, LG Chem and Fronius.

We chose these few for a couple of reasons, firstly we wanted to show diversity in areas such as price, battery type and capacity, but also include the some of the most popular brands.

Other than that, we wanted to compare batteries on the basis that they are offering homeowners a way to store their power and nothing more, rather than excluding batteries which possess certain differing qualities.

Tesla Powerwall

Tesla Powerwall

Capacity: 6.4kWh
Max Output: 2.5 - 3.3kW
Efficiency: 92.5%
DoD: 70-80%
Battery Type: Lithium-Ion
Warrantied Lifetime: 10 Years

The star child of the industry, the Powerwall certainly has the looks to match its reputation. It is an easily accessible option for people new to battery storage and solar power.

Advanced fire safety gives this system an edge however it does not come without its issues. For example, if the average ambient temperature of operation is above 30 degrees than Tesla will void the warranty.

As well as this a 2.5kW max output can be very limiting for larger homes. While in America it was hailed as the first affordable system, here this is not so much the case.

A system will cost you around $8000 roughly, which means it would have a total cost per kilowatt-hour of:

$1250/kWh

Redflow Z-Cell

Redflow Z-Cell

Capacity: 10kWh
Max Output: 3-5kW
Efficiency: 80%
DoD: 100%
Battery Type: Flow (Zinc-Bromide)
Warrantied Lifetime: 30,000 kWh

Redflow is an Australian company trying to shake things up. They have opted to go for a flow battery instead of a Lithium Ion battery. This means that the battery won’t have any overheating issues like the Powerwall or other Lithium-Ion systems.

On top of that, they have chosen to warranty the Z-cell based on usage rather than a time period. This means that it is up to you how to use this system, however, the warranty would last ten years if you used around 8kWh a day.

A system will cost you around $12,600 roughly, all up which means it would have a total cost per kilowatt-hour of:

$1260/kWh

LG Chem RESU 10H

LG Chem RESU 10H

Capacity: 9.8kWh
Max Output: 5kW
Efficiency: 95%
DoD: 95%
Battery Type: Lithium Ion
Warrantied Lifetime: 10 Years

It is not currently available in Australia, but will be later this year. Oh and we got some specs pre-release so you can compare the latest systems.

Most people haven’t heard much about this system, but when it arrives, we think it'll be quite popular.

The important things to take from this system is that it has a 5kW output, 95% efficiency, a DoD of 95% and a warranty of 10 years. It also weighs less than a 6.4kwh Tesla Powerwall.

The warranty is especially noteworthy as they are preparing to insure 80% of the system for 10 years, unlike most batteries which taper their warranties to a greater degree.

But, the most surprising thing about this system is the price point. For a capacity of 9.8kWh, it will cost $9722 after GST, meaning it will have a a cost per kilowatt-hour of:

$992/kWh

Fronius Battery

Capacity: 12kWh
Max Output: 6.4kW
Efficiency: 90%+
DoD: 80%
Battery Type: Lithium Ion
Warrantied Lifetime:5 Years

Fronius, known mostly for their inverters has also released a battery system. This system is a larger model, showing the full capacity and result stats.

As you can see the advantage to this system is the whopping 6.4kW output that it is capable of. However, given the battery stores around 12kWh, using the battery at this rate, would equate about 2 hours of usable electricity.

Secondly, the warranty for such a system is only 5 years. Overall this system is best for specialist situations, especially given that the system will cost you $15,550 overall.

This will result is a cost per kilowatt hour of:

$1296/kWh

Conclusion

We won’t try to tell which option suits you the best, however, we suggest the LG Chem 10H as a general solution. This is based on a number of things but given this is a Cost Per Kilowatt-Hour Review, $992/kWh is too good to pass up.

Other than that, the Tesla is a good all rounder with some issues which we expect to be fixed in the future, while the Z-Cell shows a promise for Australian made battery manufacturers.

SO what are your thoughts?

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